Process for retrofitting an industrial gas turbine engine for increased power and efficiency

Abstract

A process for retrofitting an industrial gas turbine engine of a power plant where an old industrial engine with a high spool has a new low spool with a low pressure turbine that drives a low pressure compressor using exhaust gas from the high pressure turbine, and where the new low pressure compressor delivers compressed air through a new compressed air line to the high pressure compressor through a new inlet added to the high pressure compressor. The old electric generator is replaced with a new generator having around twice the electrical power production. One or more stages of vanes and blades are removed from the high pressure compressor to optimally match a pressure ratio split. Closed loop cooling of one or more new stages of vanes and blades in the high pressure turbine is added and the spent cooling air is discharged into the combustor.

What is claimed is: 
     
       1. A process for retrofitting an industrial gas turbine engine of a power plant, the industrial gas turbine engine having a main compressor driven by a main turbine and a main electric generator driven by the main turbine, the main compressor having an original inlet, the process comprising the steps of:
 adding a new inlet to the main compressor, the new inlet replacing the original inlet and being capable of receiving a greater air flow than the original inlet; 
 adding a low spool with a low pressure turbine and a low pressure compressor, the low pressure turbine driving the low pressure compressor to the main turbine such that the low pressure turbine is driven by exhaust from the main turbine; 
 adding a variable inlet guide vane assembly to an inlet side of the low pressure turbine; 
 adding a compressed air line connecting the low pressure compressor to the new inlet of the main compressor such that compressed air from the low pressure compressor flows into the main compressor; and 
 removing at least one stage of rotor blades and stator vanes from the main compressor. 
 
     
     
       2. The process for retrofitting the industrial gas turbine engine of the power plant of  claim 1 , the industrial gas turbine engine of the power plant further having a main combustor, the process further comprising the steps of:
 installing at least one new row of turbine stator vanes in the main turbine in which the at least one new row of turbine stator vanes have a closed loop cooling circuit; 
 providing a source of compressed cooling air for cooling of the at least one new row of turbine stator vanes, the source of compressed cooling air corresponding to one of the compressed air from the low pressure compressor and compressed air from a cooling air compressor different from the low pressure compressor and main compressor; and discharging spent cooling air from the new row of turbine stator vanes upstream of the main combustor, the main combustor producing a hot gas stream for the main turbine. 
 
     
     
       3. The process for retrofitting the industrial gas turbine engine of the power plant of  claim 2 , and further comprising the steps of:
 bleeding off the compressed cooling air from the main compressor; 
 intercooling the compressed cooling air with an intercooler; 
 increasing a pressure of the compressed cooling air to a pressure higher than an outlet pressure of the main compressor to produce a higher pressure cooling air; and 
 passing the higher pressure cooling air through the closed loop cooling circuit in the at least one new row of turbine stator vanes. 
 
     
     
       4. The process for retrofitting the industrial gas turbine engine of the power plant of  claim 2 , and further comprising the steps of:
 compressing ambient air with an external cooling air compressor to a pressure higher than an outlet pressure of the main compressor to produce a higher pressure cooling air; 
 intercooling the higher pressure cooling air with an intercooler; and 
 passing the higher pressure cooling air through the closed loop cooling circuit in the at least one new row of turbine stator vanes. 
 
     
     
       5. The process for retrofitting the industrial gas turbine engine of the power plant of  claim 2 , and further comprising the steps of:
 bleeding off the compressed cooling air from an outlet of the main compressor; 
 intercooling the compressed cooling air with an intercooler; 
 increasing a pressure of the compressed cooling air output by the intercooler to a pressure higher than an outlet pressure of the main compressor to produce a higher pressure cooling air; and 
 passing the higher pressure cooling air through the closed loop cooling circuit in the at least one new row of turbine stator vanes. 
 
     
     
       6. The process for retrofitting the industrial gas turbine engine of the power plant of  claim 2 , and further comprising the steps of:
 bleeding off the compressed cooling air from an outlet of the main compressor; 
 increasing a pressure of the compressed cooling air to a pressure higher than an outlet pressure of the main compressor to produce a higher pressure cooling air; 
 intercooling the higher pressure cooling air with an intercooler; and 
 passing the higher pressure cooling air through the closed loop cooling circuit in the at least one new row of turbine stator vanes. 
 
     
     
       7. The process for retrofitting the industrial gas turbine engine of the power plant of  claim 2 , and further comprising the steps of:
 bleeding off at least a portion of the compressed air for use as the compressed cooling air for the at least one new row of turbine stator vanes; and 
 cooling and compressing the compressed cooling air to a pressure higher than an outlet pressure of the main compressor. 
 
     
     
       8. The process for retrofitting the industrial gas turbine engine of the power plant of  claim 1 , and further comprising the steps of:
 adding a variable inlet guide vane assembly to both the main compressor and the low pressure compressor. 
 
     
     
       9. The process for retrofitting the industrial gas turbine engine of the power plant of  claim 1 , further comprising the step of:
 replacing the main electric generator with a new electric generator that has a greater electrical power production than the main electric generator. 
 
     
     
       10. A process for retrofitting an industrial gas turbine engine of a power plant, the industrial gas turbine engine having a main compressor driven by a main turbine, a power turbine driven by the main turbine, and a main electric generator driven by one of the main turbine and the power turbine, the main compressor having an original inlet, the process comprising the steps of:
 adding a new inlet to the main compressor, the new inlet replacing the original inlet and being capable of receiving a greater air flow than the original inlet; 
 adding a low pressure compressor to be driven by the power turbine; 
 adding a variable inlet guide vane assembly to an inlet side of the power turbine; 
 adding a compressed air line connecting the low pressure compressor to the new inlet of the main compressor such that compressed air from the low pressure compressor flows into the main compressor; and 
 removing at least one stage of rotor blades and stator vanes from the main compressor. 
 
     
     
       11. The process for retrofitting the industrial gas turbine engine of the power plant of  claim 10 , further comprising the steps of:
 removing the main electric generator from the power turbine; and 
 adding a new electric generator to be driven by the main compressor, the new electric generator having a greater electrical power production than the main electric generator. 
 
     
     
       12. The process for retrofitting the industrial gas turbine engine of the power plant of  claim 11 , and further comprising the steps of:
 adding a gearbox between the new electric generator and the main compressor. 
 
     
     
       13. A power plant with a retrofitted industrial gas turbine engine, the power plant comprising:
 an original main compressor driven by a high pressure turbine with a high pressure combustor; 
 a replacement inlet on the original main compressor, the replacement inlet being capable of producing a greater compressed air flow than an original inlet of the original main compressor; 
 an original electric generator; 
 a low spool with one of a new low pressure turbine and an original power turbine driven by exhaust gas from the high pressure turbine, and a new low pressure compressor driven by the low pressure turbine; 
 a new compressed air line connecting the new low pressure compressor to the replacement inlet of the original main compressor; 
 a new variable inlet guide vane assembly for the one of the new low pressure turbine and the original power turbine; and 
 the original main compressor having been modified by removal of at least one stage of stator vanes and rotor blades. 
 
     
     
       14. The power plant of  claim 13 , wherein the high pressure turbine has at least one row of new stator vanes with a closed loop cooling circuit, the power plant further comprising:
 a source of compressed cooling air; and 
 a compressed air cooling circuit to deliver compressed cooling air to the closed loop cooling circuit of the at least one row of new stator vanes and discharge spent cooling air in front of the high pressure combustor. 
 
     
     
       15. The power plant of  claim 14 , and further comprising:
 a new boost compressor between the source of compressed cooling air and the at least one row of new stator vanes to increase the pressure of the compressed cooling air; and 
 a new intercooler between the source of compressed cooling air and the at least one row of new stator vanes to cool the compressed cooling air.